The "what program" part depends on which program you want stopped.
You can press Ctrl + Alt + Del on your keyboard (at the same time) To see what processes are presently running.
You can also, right click on a process and end it (if you know which process that you want stapped. (but this will startup the next time you restart your computer anyway - hence the above link to Startup Control Panel)

Please try unticking as many startup processes (using the above download link) then restart your computer (the only one to usually keep in Startup is AntiVirus)